The invention relates to a process for the production of a pencil, wherein a lead or core stick is introduced into a groove in a first housing portion and then a second housing portion provided with a groove is applied to the first housing portion with the lead or core stick and the lead or core stick is glued to the housing portions and the two housing portions are glued to each other.
The so-called `bonding process` is known for the production of a pencil, wherein an adhesive is applied to the lead or core stick at a plurality of locations in an annular configuration or in a network-like structure. The bonding process therefore serves for fixing the lead or core stick in the groove in a first housing portion and for fixing the lead or core stick between the two housing portions which are provided with corresponding grooves. That process suffers from the disadvantage that it is only possible with difficulty to apply an adhesive to a lead or core stick in the specified manner, that is to say using the bonding procedure.
It is also known for finished leads or core sticks to be coated with a hard, that is to say inflexible layer of lacquer or plastic material in order to increase the breaking strength of the leads or core sticks. The same process, that is to say coating finished leads with a hard inflexible layer of lacquer or plastic material for increasing the breaking strength, is used for example, in relation to leads or core sticks with water-soluble dyes, as are used for example in so-called indelible pencils, or in relation to emulsifier-bearing pigmented textures, as are used for example in so-called water-paintable pencils, in order to prevent diffusion of the dye or constituents of a water-soluble pigment into the wood of the housing portions during the operation of glueing the leads or core sticks between the housing portions.
In the case of water-based compositions for leads or core sticks, it was previously necessary to produce leads or core sticks from each composition batch, as samples thereof, and to dry same, in order to detect and take account of or compensate for the shrinkage of the sample leads or core sticks, which is caused by the drying operation and which varies in dependence on the composition used. That not only involves a considerable amount of time but also constitutes an uncertainty factor in the production of such leads or core sticks. In addition, in the operations of cutting and applying the extruded lead or core stick portion, it is not possible reliably to exclude elongation or upsetting of the leads or core sticks, which can result in fluctuations in the thickness of the leads or core sticks. Besides those tolerances in regard to the leads or core sticks, the grooves in the housing portions my also have certain tolerances, that is to say for example they may be of different depths, which can result in difficulties when the leads or core sticks are being glued into position in the grooves, that is to say between the two housing portions.